Cos 70° - sin 140° - cos 10°

Question

Cos 70° - sin 140° - cos 10°

Answer 1

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0.4921510727
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Answer 2

Cos60-sin140=cosП/3-sin7П/9=sinП/6-sin7П/9=sin(-11П/18)=sin(-110)=-sin(110)=sin(90+30)=sin30=1/2

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